Power over Ethernet (PoE), which is outlined in IEEE Std 802.3™-2005 clause 33 (the PoE standard), refers to a technique for delivering power and data to an electronic device via a network cable, such as a twisted pair Ethernet cable. Typically, a PoE system includes power sourcing equipment (PSE) to provide a power supply via Ethernet cabling to one or more electronic device, which may be referred to as powered devices. PoE reduces the need for a separate power source to deliver power to attached powered devices. Such powered devices may include voice over Internet protocol (VoIP) telephones, wireless routers, security devices, field devices to monitor process control parameters, data processors, and the like.
Generally, the PoE standard specifies that a powered device include a PoE compatible control device and a switch regulator device that takes a voltage supplied by the network cable (e.g. 36 to 57 Volts) and reduces the received voltage to a lower voltage level for use by circuit components of the powered device. For example, the lower voltage level may be within a range of 1.2 to 5 Volts.
Conventionally, powered devices utilize a PoE controller that is coupled to external diode bridges and external voltage protection devices. The PoE controller may be protected using external over-voltage or surge protection circuitry, but over-voltage conditions may still appear at an input of the switching regulator. To prevent breakdown due to over-voltage conditions, a high-voltage external switch may be used, which may have a high turn-on voltage, but which may increase the overall power consumption of the powered device.
Therefore, there is a need for an improved integrated circuit with a switching regulator and with PoE functionality.